Which of the following is correct?

Options

A. AgBr shows both Schottky and Frankel defect
B. Frenkel defect is shown by ionic solids where there is large difference in size of anion and cation
C. In Frankel defect, dielectric constant of crystal increases
D. All are correct

Answer

To solve the question, we need to analyze the options provided regarding the defects in ionic compounds, specifically AgBr (Silver Bromide). The question asks which of the following statements is correct regarding the defects in AgBr.

### Step-by-Step Solution:

1. **Understanding Ionic Compounds**:
- AgBr is an ionic compound composed of Ag⁺ (silver cation) and Br⁻ (bromide anion).
- Ionic compounds can have defects in their crystal structure, which can affect their properties.

**Hint**: Recall that ionic compounds consist of cations and anions, and their arrangement can be disrupted by defects.

2. **Types of Defects**:
- **Schottky Defect**: This occurs when equal numbers of cations and anions are missing from the lattice, maintaining charge neutrality.
- **Frenkel Defect**: This occurs when a cation is displaced from its lattice site to an interstitial site, creating a vacancy at the original position.

**Hint**: Remember the definitions of Schottky and Frenkel defects and how they relate to the arrangement of ions in the crystal lattice.

3. **Analyzing AgBr**:
- AgBr can exhibit both Schottky and Frenkel defects due to the size difference between Ag⁺ and Br⁻ ions.
- In the case of Frenkel defects, the cation (Ag⁺) is smaller than the anion (Br⁻), allowing it to fit into an interstitial site.

**Hint**: Consider the size of the cations and anions in AgBr and how this affects the type of defects that can occur.

4. **Effect on Dielectric Constant**:
- The presence of defects in a crystal can influence its dielectric properties. For example, the dielectric constant may increase due to the mobility of ions in the presence of defects.

**Hint**: Think about how the movement of ions in a crystal lattice can affect its electrical properties.

5. **Conclusion**:
- Based on the analysis, AgBr can exhibit both Schottky and Frenkel defects due to the size difference between its cations and anions.
- Therefore, the correct answer to the question is that both types of defects can occur in AgBr, and the statement regarding the increase in dielectric constant due to these defects is also correct.

**Final Answer**: The most appropriate answer is option 4, which states that AgBr exhibits both Schottky and Frenkel defects, and the dielectric constant increases.